This invention relates to an integrated circuit having an input protection device including a bipolar transistor to shunt current away from sensitive areas of the circuit during an e.s.d. (electrical surge discharge) event.
Metal oxide semiconductor integrated circuits (MOS) ICs are extremely sensitive to surge discharges. This is particularly true of the gate oxide regions in the circuit. In order to protect such ICs, it is known to provide a bipolar transistor in the input protection circuit to shunt current away from these sensitive areas during a discharge event. However, the current handling capability of such devices is inherently limited due to the fact that the voltage drop across the high resistivity base limits emitter current to flowing only along the extreme edge of the emitter.
An object of the present invention is to alleviate the aforementioned disadvantage by increasing the current handling capability of such input protection devices.